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Germinating cannabis seeds humidity dome

Growing Strong Seedlings

A healthy, productive indoor garden cycle starts with strong seedlings. Here are a few basic propagation tips to help your plants reach their true genetic potential.

Giving your plants a strong head start is an important first step towards achieving success in your indoor garden. If your seedlings are weak and spindly, they may not make it off the propagation bench. Even if seedlings do survive, they may never reach their true genetic potential, so following a few propagation basics is well worth the time and effort.

Soaking seeds in water before planting. Source: Gheorghe Mindru/Shutterstock

Soak Yours Seeds Before You Start

Whenever possible, it’s best to use fresh seeds that have been stored in a cool, dark place. Fresh seeds are loaded with starches and stored nutrients, and typically have a good germination rate when given adequate moisture and warmth. If you have older seeds or seeds that haven’t been stored under ideal conditions, a few extra precautions should be taken.

Kelp extracts make a great seed soak for older seeds, as kelp is loaded with natural growth hormones and contains many beneficial trace elements. One of the hormones found in seaweed extracts is called gibberillic acid. In nature, gibberillic acid triggers the release of enzymes in the seeds that begin the germination process. Soaking seeds overnight in seaweed extracts may improve germination rates by up to 30%.

Place your seeds into rockwool for a better watering and growing. Source: masterpict/Shutterstock

In hydroponic applications, stonewool starter cubes are a good choice for starting seeds. A sheet of stonewool starter cubes fits perfectly in a standard nursery tray, and it has the perfect air- to water-holding capacity. Just make sure you condition the stonewool with pH-adjusted water before planting.

For best results, soak the starter cubes for a few minutes in water with a pH of about 5.5. The conditioning solution will neutralize the limestone dust left over from the manufacturing process and provide plenty of moisture for germinating seeds. Pour off the excess water so the stonewool isn’t sitting in a puddle of water, then simply plant one seed in each starter cube.

LED Grow Light – Full Spectrum lamp over seeds. Source: Bobkov Evgeniy/Shutterstock

Give Your Seedlings Some Full-spectrum Light

It’s also a good idea to cover the propagation tray with a humidity dome and place the tray under full-spectrum lights. The dome will keep the relative humidity in the propagation tray at about 98%—ideal for germinating seeds—and the full-spectrum lights will help keep the seedlings from stretching once they germinate. Seedlings don’t need much light intensity. Two standard fluorescent lamps over a nursery tray are adequate, but many gardeners, including myself, prefer four lamps.

Full-spectrum fluorescent grow lamps work best. The blue end of the spectrum helps seedlings remain short and stocky, and the red end of the spectrum helps stimulate root growth. Just keep the lamps a few inches above the growing tips and raise the lamps as needed. Also, remember to remove the humidity dome after all of the seeds have germinated and started to grow. Keeping the humidity dome on too long can set up an environment for fungal pathogens.

Give Your Seedlings Some Bottom Heat

Bottom heat is also beneficial, especially for germinating tropical seeds. Most heating mats are set at the factory to provide a temperature of 78°F. The warm temperature helps activate enzymes such as amylase, the enzyme that breaks down starches into sugars, which provide energy for cell division and growth.

Remember not to use bottom heat when germinating cool-weather crops such as lettuce and spinach. Warm temperatures actually inhibit germination in cool-weather crops. Check your seed packages for any other special considerations. For example, some seeds may need to be cold-treated before they can germinate, and a few native seeds need to be scratched or treated with acids before they can germinate. Fortunately, most garden variety seeds are easy to germinate with little special treatment.

After the seeds germinate, the bottom heat should be reduced or removed. The warmer the water temperature, the less dissolved oxygen the water can hold. Remember, it’s not overwatering that kills the plant, it’s lack of oxygen. If the water temperature exceeds 78°F, it can’t hold enough dissolved oxygen and it sets up an environment for anaerobic fungi. Anaerobic fungi grow in stagnant, oxygen-deprived water, and they are the bad guys that cause root rot. After the seeds germinate, try to maintain the water temperature between 68 and 75°F for best results.

Seedling tray where first true leaves have developed. Source: New Africa/Shutterstock

Starter Fertilizers for Seedlings

Seeds contain all of the minerals and nutrients necessary to begin growing, so they can be germinated with water only. Once the first true leaves start to appear, however, they need a starter fertilizer. The first leaves that pop out of the seed are not true leaves; they are the embryonic leaves that are formed inside the seed. The second sets of leaves are the plant’s first true leaves. When they appear, it means the seedling is actively growing and that it is ready for a mild fertilizer.

During the first few weeks, use a full-spectrum fertilizer that includes trace elements such as iron, copper, manganese and zinc. The trace metals are cofactors that actually turn on enzymes used for photosynthesis and cellular metabolism. Also, make sure the pH is kept in the slightly acidic range, somewhere between 5.8 and 6.4. If the pH rises much past 6.5, iron starts to become unavailable to the plant. Iron is a catalyst for the formation of chlorophyll, essential for photosynthesis.

If the pH rises above 7.5, all of the metal catalysts start to become unavailable and can slow down new growth. Zinc, for example, activates the enzymes necessary for indole-3-acetic acid (IAA) production—the growth hormone responsible for initiating root production.

Adequate phosphorus is also important for faster root strike and better establishment of the plant. Phosphorus is the energy element. It energizes the rooting process, and extra phosphorus is included in most commercial starter fertilizers. With just a little extra phosphorus, it is possible to see as much as 20% more roots.

Tomato Seedling with visible root. Source: Lyona/Shutterstock

Root Stimulants for Seedlings

Starter fertilizers provide all of the essential minerals that seedlings need, but organic bio-stimulants aid with the uptake of minerals. For example, humic and fulvic acids aid with the uptake of iron and other trace minerals. Humic acid is an intermediate chelator. “Chela” means “claw,” so humic acid molecules attach to mineral ions like a claw, holding them tightly enough to keep them from getting locked up in the soil, but loosely enough to release them to the root hairs on demand. Humic and fulvic acids also help to neutralize pH. In nature, humic acids raise the pH of acid soils and lower the pH of alkaline soils.

For even better results, combine humic acid with seaweed extracts. When used together in a 5:2 ratio, humic acid and seaweed work 50% better than either product alone. The combination stimulates root development, producing more lateral root growth and more root mass. Seaweed extracts also contain B-vitamins and amino acids that stimulate cellular metabolism and further aid with the uptake of minerals.

For example, some amino acids stimulate root cells to open up calcium ion channels, allowing calcium ions to be taken up thousands of times faster than simple osmosis. Calcium helps seedlings develop thicker stems and stronger cell walls. Plus, calcium activates the enzymes that pump the growth hormones to the growing tips.

Microbial Inoculants for Seedlings

Treating seedlings with microbial inoculants is also a good idea. Some microbes fix nitrogen from the air and feed it to the plant, others solubilize phosphorus, and some produce plant protection agents and rooting hormones. For example, some micro-organisms produce the amino acid tryptophan on the surface of the roots. The root cells easily absorb the tryptophan and transport it to the leaves, where it is converted into IAA. The IAA is then pumped to the roots to stimulate the growth of new root hairs.

Beneficial microbes also produce siderophores. The word siderophore literally means “iron carrier.” One of the strongest chelators of iron in nature, siderophores act indirectly as plant protection agents. As beneficial bacteria colonize the root surface, siderophores sequester iron and make it unavailable to foreign invaders so the roots are protected from root pathogens such as pythium and rhizoctonia. Some soilless mixes take advantage of the process by adding certain species of bacillus subtilis to the blend and calling it a biofungicide.

Propagation is easy if you have the right tools and follow a few simple instructions. Just give the seeds a good soaking, and provide adequate light and warmth. Afterwards, it only takes a little coaxing to grow strong, healthy seedlings with thick stems and dark green foliage. Propagation is the least expensive part of indoor growing, so don’t be afraid to throw in a few extra seeds, and always select the best of the best!

Humidity dome for germination?

Ive heard different opinions regarding this, this is my first time using a heat mat and humidity dome, some say dont use a humidity dome when germinating because it could cause mold to grow on the seed.

Ive always just used the paper towel and glass mug method and then transferred to a make shift humidity dome after leaves. Ive also seen some say dont use a humidity dome at all for any stage although personally Ive had better luck with a humidity dome then without, whats your take on the dome for germination?

Well-Known Member

Well. to quote each his own. ..sorry could not resist, its on your member profile.

But. on the humidity dome, I use one and have every time and it works for me. I never had any issues with mold or fungus or anything else. I think the mold and fungus part comes from how wet your soil really is. Mine is damp, not soaked. All of my seeds have popped without issues doing it with the dome, as a matter of fact, just popped 4 and they came up in 4 days. I do take the dome off occasionally during the day, maybe once or twice at most for 10 minutes or so, but then it is back on until I see stable seedlings.

Dalek Supreme
Well-Known Member

The dome is for keeping the seed from drying out. You want warm, moist, not saturated, and not dried out.

Keep things clean.

Well-Known Member

Just popped 14 sour bubble and 14 sour grape using humidity dome. I’m n the same place as OP. I’ve used my aero garden to germinate seeds in the past and I’ve used the moist paper towel method. Like I said 3 days ago I put some SB and SG seeds in Rockwood in the humidity dome. I can see the sprouts coming on 75% now

Well-Known Member

Leaves dont function in a humidity dome, its simple logic and why they are so effective for clones. As soon as your seedlings break the surface you discard the dome, if you find your seedlings do better with one on then you have other issues you need to work on before you can hit the standards of millions of growers who do just fine without one.

Theres no argument here, just the right way of doing somthing versus all the bs that gets perpetuated by half arsed growers.

Well-Known Member

I germ inside a 12 x 16 inch sealable baggie. Whatever you choose the important thing is it has to be sealed to be most effective. Biggest threat is the seeds drying out.

How to Germinate Cannabis Seeds

Join us as we detail the most effective methods in how to germinate cannabis seeds, along with information that will help you understand marijuana seeds from a new perspective.

Germinating cannabis seeds may seem straightforward, but it’s actually a subtle art that many have yet to master. This is the beginning of a long and arduous journey, so it’s necessary that your cannabis plants start off on the right foot.

How to Germinate Cannabis Seeds : Seeds and Dispersal

How do Cannabis Plants Produce Seeds?

Cannabis Breeders

Anatomy of a Cannabis Seed

Materials Needed for Germinating Cannabis Seeds

General Requirements for Cannabis Seed Germination

Cannabis Seed Germination Methods

Cannabis Seeds and the Scarification Method

How to Germinate Cannabis Seeds : Seeds and Dispersal

A seed is an embryonic plant. Just as humans are embryos at the earliest stage of life, so are seeds.

In the case of cannabis plants, their seeds are produced to enable new generations to spread across a landscape with ease.

Cannabis seeds, like all other seeds, are the result of reproduction between plants. Each plant has evolved throughout millions of years to adapt to their surroundings; thus, they’ve also made their seeds adapt to certain dispersion methods.

Since seeds eventually grow into a plant, their range of mobility is fixed. They cannot move across the land as animals do; therefore, their seeds must disperse away from their immediate vicinity.

Plants have come up with ingenious ways to disperse their seeds, using wind, water, animals, and even though their own physical force to throw them out.

Some seeds are equipped with “wings,” which are adaptations that allow the seed to ride the current of the wind for an extended period of time so that it’s dispersed away from its mother.

Many are adapted for water submersion, while others are capable of being digested and remaining intact or to latch onto the fur of a passing animal.

The ways that seeds are dispersed are many, but cannabis has recently found an interesting partner to help in its dispersal. Humans are the leading cause for transporting cannabis seeds throughout the world.

Before their popularity in the last 50 years, many cannabis species were endemic to specific regions throughout the globe.

Now, with the help of human intervention, cannabis seeds are found in the suburbs, cities, and farms. Each cannabis seed is prized, and we do our best to make sure each and every seed germinates so that no seed is wasted.

This is the general understanding between us and cannabis seeds, in which the most legendary strains have been found in unnamed “bag seed.”

Each marijuana seed carries the potential of a legendary strain within its shell, and like you, we’re always concerned with making sure our cannabis seeds make it past the germination process.